The present invention relates to a key backlight for a cell phone or the like having an operation key section and, more particularly, to a key input device including a light-emitting means for lighting or blinking an operation key section in different modes or colors in accordance with key operation.
In a cell phone having an operation key section constituted by a plurality of keys for operating the cell phone, e.g., inputting a telephone number or mail using characters, the keys of the operation key section are formed from a transparent or translucent material. In addition, a plurality of light-emitting portions (key backlights) are arranged on the bottom sides of these keys to light or blink the operation key section in different modes or colors in accordance with the operation of the cell phone.
Japanese Patent Laid-Open No. 2001-217904 discloses a technique of using an operation key section as a notification means and display means by utilizing the above operation.
FIG. 7 shows the outer appearance of a cell phone with an operation key section lighting function disclosed in the above reference. An operation key section 54 formed from a translucent member is comprised of a plurality of keys such as dial number keys 54a, a signal transmission/reception key, an on-hook key 54b, a mail key 54c, and various setting keys. The operation key section 54 also serves as an input operation means for a control section in the cell phone body.
Multicolor light-emitting portions (key backlights) 55 are arranged in correspondence with the respective keys. Each light-emitting portion is constituted by a multicolor LED or the like capable of emitting two or more different color beams. The emission mode of each multicolor light-emitting portion 55 is controlled by the control section in the cell phone body. In addition, the multicolor light-emitting portions 55 emit light beams in predetermined colors in accordance with various kinds of operation of the cell phone.
For example, musical notes are assigned in advance to the multicolor light-emitting portions 55 and the corresponding keys, and the multicolor light-emitting portions 55 are made to emit light beams in different colors in accordance with the musical notes of melody sounds generated by the melody sound generating section in the cell phone body. Alternatively, when a plurality of melodies are set, the multicolor light-emitting portions are made to emit light beams in different colors in accordance with the kinds of melodies. This makes it possible to discriminate, in accordance with an emission color, who has made a call.
In addition, when mail is received, the multicolor light-emitting portion 55 corresponding to a numeric key indicating the number of incoming calls is made to emit light in accordance with the number of received mail.
When the dial number key 54a lighted by the light emitted by the multicolor light-emitting portion 55 is pressed, the contents of the mail are displayed on a display section 53.
Many functions as added values, e.g., a mail function and browser function, are added to recent cell phones.
For example, in performing mail transmission using the mail function, the user must input a mail message using keys of the operation key section of the cell phone.
The operation key section, however, has ten-odd keys at most. The user must input characters in various modes, e.g., the numeric input mode, kanji input mode, and alphabet input mode using such limited number of keys. In general, therefore, the character input modes are switched by a character input mode changing key to allow the user to input various kinds of characters by key input in a desired character input mode while checking an icon indicating a character input mode, which is displayed on a corner of the display screen.
As described above, the user must set a desired input mode while checking the currently used input mode with a small icon displayed on a corner of the display screen.
If the character input mode is changed by an input error unintended by the user, he/she tends to overlook the change in mode with such a small icon. As a consequence, the input error makes the user waste extra time creating a mail message.